Gorillas

Gorillas are some of the most powerful and striking animals, not only for their size and force, but also for their gentle human like behavior. They play a crucial role in local biodiversity, roaming through large territories and helping, for example, to spread the seeds of the fruit they consume.

Physical description

The largest living primates, gorillas are stocky animals with broad chests and shoulders, large hands, and forearms that are much shorter than the upper arm. The face is black and hairless, with small eyes that are close together and large, prominent nostrils.

Adult males are identified by a sagittal crest along the midline of the skull and an area of white hair on the back, which is why they are known as ‘silverbacks.’

Eastern gorillas are the larger species, and have darker and longer fur, particularly on their arms. In comparison, western lowland gorillas have shorter hair that is gray or brown with a tendency to red on their heads.

To add to these differences, lighter hair on western silverbacks stretches to their thighs, as opposed to the more defined patch in the otherwise dark backs of eastern gorillas.

Size: Adult males weigh up to 200kg, with females around half this size. Can reach a height of 1.2-1.7 meters when standing on 2 feet.

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Forest families

Gorillas typically live in the lowland tropical rainforests of Central Africa, although some subspecies are found in montane rainforest (between 1,500 and 3,500 meters) and in bamboo forest (between 2,500 to 3,000 meters).

Social structure
Gorillas have a well-developed social structure, forming stable family groups in which the dominant male keeps his position for years.

Group size is usually 5-10 individuals, but can vary from 2 to over 50 members. According to group size, habitat quality and food availability, a group's home range may vary from 5 to over 30km², with frequent overlap between group ranges.

If a male leaves a group, he wanders alone for a number of years, then sometimes establishes a range next to or overlapping that of his old group.

Adult males that stay in a group are generally the offspring of the dominant male and eventually will take over leadership.

As a general rule, female gorillas leave their group at maturity to join other groups or single males, although cases of females reproducing in their original groups are known.

Life cycle
Females become sexually mature at 7-8 years old, but do not start to breed until several years later. Males mature later than females, with few breeding before the age of 15 years.

High infant mortality, a long gestation (8.5 months), a tendency to single births, and a prolonged period of maternal care mean that, on average, only one baby is reared in a 4-6 year period. Females generally give birth to only three or four surviving young during their reproductive life.

The mortality rate for gorillas less than one year old is high, but for adults the rate is only 5%. In the wild, they might live to be 40 years old. In the United States, a captive gorilla was reported to have lived to the age of 54.

Diet
Gorillas are mainly herbivorous (vegetarian) and spend almost half of the day feeding on stems, bamboo shoots, and a variety of fruits, supplemented with bark and invertebrates.

At some sites, western lowland gorillas have been known to break open termite nests and feed on the larvae.

Western lowland gorillas favor areas of dense vegetation such as the rainforest in Dzanga Sangha National Park.

Population & distribution

Many gorilla populations have declined or completely disappeared over the past few decades.

The lowland subspecies are more numerous and widespread than the upland and mountain subspecies. Mountain gorillas are the only gorillas to show an increase in numbers, but the overall population size is still very low.

The Cross River gorilla is currently the world’s rarest great ape, with a population of only around 250-300 restricted to a small area of highland forest on the border of Cameroon and Nigeria.

There is no reliable estimate of the eastern lowland gorilla population; however at one time it could have reached 17,000 individuals.

The total population of mountain gorillas is around 880 individuals, split into two separate groups.

Priority species

As a great ape, gorillas are a WWF priority species. WWF treats priority species as one of the most ecologically, economically and/or culturally important species on our planet. As such, we are working to ensure gorillas can live and thrive in their natural habitats.

WWF in the field

Angelique Todd, Gorilla Expert

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How you can help

Visit the gorillas! Money earned through gorilla tourism contributes significantly to the conservation of the species – providing funds for conservation projects and creating jobs and bringing other benefits to local communities living near gorillas. To visit the gorillas of Dzanga-Sangha in Central African Republic, contact: info@dzanga-sangha.org.

Give a gift! Buy a "Gorilla's Paradise" WWF gift and help support the Gamba Complex of protected areas in Gabon – home to western lowland gorillas as well as hippos, elephants and much more.